1. Technical Field
This invention relates to polarization of a coaxial flexible piezoelectric cable.
2. Related Arts
Generally, as shown in FIG. 5, a coaxial flexible piezoelectric cable comprises a piezoelectric body tube 3 comprising a coaxial flexible piezoelectric body 2 formed surrounding a core electrode 1, an outer electrode 4 formed on the outer surface of the piezoelectric body tube 3, and a protective coat layer (not shown) formed surrounding the outer electrode 4.
Hitherto, the flexible piezoelectric body cable is polarized as follows:
Document 1 (xe2x80x9cAtuden ceramic funmatu to gouseigomu tokaranaru atudenfukugouzairyou,xe2x80x9d Funntai to kougyou, 22kan, 1gou, 50-56 pp) shows that a high voltage is applied between the core electrode 1 and the outer electrode 4 for polarizing the coaxial flexible composite piezoelectric body 2. This is also disclosed in U.S. Pat. No. 4,568,851. Since the directions of spontaneous polarization of ceramic particles are made identical with the electric field direction by polarization, piezoelectricity is given to the coaxial flexible composite piezoelectric body 2. In this point, the polarization bears an important role.
Further, a coaxial flexible piezoelectric cable comprises a piezoelectric body tube 203 comprising a coaxial flexible piezoelectric body 202 formed surrounding a core electrode 201, an outer electrode 204 formed on the outer surface of the piezoelectric body tube 203, and a protective coat layer 205 formed surrounding the outer electrode 204, as shown in FIG. 9.
In the method, when a high voltage is applied between the core electrode 401 and the outer electrode 404, if the coaxial flexible piezoelectric body 402 contains a defect such as a minute crack or gap, discharge occurs in the defective part, and the core electrode 401 and the outer electrode 404 are electrically short-circuited. Consequently, it is made impossible to apply a high voltage between the core electrode 401 and the outer electrode 404 and thus it is made impossible to polarize the coaxial flexible piezoelectric body 402 (usually, having a length of several hundred meters or more). Since the presence of a defect cannot be detected until a high voltage is applied between the core electrode 401 and the outer electrode 404, in other words, until completion as a coaxial flexible piezoelectric body cable except for polarizing, manufacturing becomes unstable and yield is reduced.
Thus, the following polarization method of the flexible piezoelectric body cable is possible:
As shown in FIG. 17, a polarization apparatus is possible wherein a piezoelectric body tube 403 comprising a coaxial flexible piezoelectric body 402 formed surrounding a core electrode 401 is disposed on a block-like conductor 406 and DC voltage generation means 409 is connected to the block-like conductor 406 and the core electrode 401 through leads 408 and 481 for applying a DC voltage. According to the polarization apparatus, the coaxial flexible piezoelectric body 402 is disposed on the block-like conductor 406 and thus the block-like conductor 406 acts as an outer electrode 404. Therefore, a DC voltage can be applied between the block-like conductor 406 and the core electrode 401 by the DC voltage generation means 409 for polarizing the coaxial flexible piezoelectric body 402 of the portion disposed on the block-like conductor 406.
[Problems to be Solved]
However, when a high voltage is applied between the core electrode 1 and the outer electrode 4, if the coaxial flexible composite piezoelectric body 2 contains a defect such as a minute crack or gap, minute discharge occurs in the defective part. This minute discharge causes the conductive material forming the core electrode 1 and the outer electrode 4 and the material forming the coaxial flexible composite piezoelectric body 2 to be thermally evaporated and scattered, short-circuiting the core electrode 1 and the outer electrode 4. Consequently, it is made impossible to apply a high voltage between the core electrode 1 and the outer electrode 4 and thus it is made impossible to polarize the coaxial flexible composite piezoelectric body 2 (usually, having a length of several hundred meters or more); this is a problem.
Since the presence of a defect cannot be detected until a high voltage is applied between the core electrode 1 and the outer electrode 4, in other words, until completion as a coaxial flexible piezoelectric cable except for polarizing, manufacturing becomes unstable and yield is reduced; this is also a problem.
Further, the method in the related art involves the following problems: When a high voltage is applied between the core electrode 201 and the outer electrode 204, if the coaxial flexible piezoelectric body 202 contains a defect such as a minute crack or gap, minute discharge occurs in the defective part. This minute discharge causes the material forming the flexible piezoelectric body 202 to be thermally evaporated and scattered, short-circuiting the core electrode 201 and the outer electrode 204. Consequently, it is made impossible to apply a high voltage between the core electrode 201 and the outer electrode 204 and thus it is made impossible to polarize the coaxial flexible piezoelectric body 202 (usually, having a length of several hundred meters or more).
Since the presence of a defect cannot be detected until a high voltage is applied between the core electrode 201 and the outer electrode 204, in other words, until completion as a coaxial flexible piezoelectric cable except for polarizing, manufacturing becomes unstable and yield is reduced.
Still further, the method in the related art involves the following problems: When a high voltage is applied between the core electrode 301 and the outer electrode 304, if the coaxial flexible piezoelectric body 302 contains a defect such as a minute crack or gap, minute discharge occurs in the defective part. This minute discharge causes the material forming the flexible piezoelectric body 302 to be thermally evaporated and scattered, short-circuiting the core electrode 301 and the outer electrode 304. Consequently, it is made impossible to apply a high voltage between the core electrode 301 and the outer electrode 304 and thus it is made impossible to polarize the coaxial flexible piezoelectric body 302 (usually, having a length of several hundred meters or more).
Since the presence of a defect cannot be detected until a high voltage is applied between the core electrode 301 and the outer electrode 304, in other words, until completion as a coaxial flexible piezoelectric cable except for polarizing, manufacturing becomes unstable and yield is reduced.
Still further, the method in the related art involves the following problem:
If a DC voltage is applied to the block-like conductor 406 and the core electrode 401 by the DC voltage generation means 409, a force of causing the coaxial flexible piezoelectric body 402 and the block-like conductor 406 to attract each other is generated by an electrostatic force. Thus, to move the piezoelectric body tube 403, a frictional force occurs between the coaxial flexible piezoelectric body 402 and the block-like conductor 406, making it impossible to move the piezoelectric body tube 403. If the piezoelectric body tube 403 can be moved, a large force is required.
[Means for Solving the Problems]
To solve the above-described problems, according to the invention, there is provided a polarization apparatus of a coaxial flexible piezoelectric cable, comprising a first conductor drum having a plurality of grooves for coming in contact with a roughly half peripheral surface of a piezoelectric body tube comprising a coaxial flexible piezoelectric body formed surrounding a core electrode and being rotated in a given direction, a second conductor drum being placed behind the first conductor drum and having a plurality of grooves for coming in contact with another roughly half peripheral surface of the piezoelectric body tube, winding means being placed behind the second conductor drum for winding the piezoelectric body tube, conduction means for electrically connecting the first conductor drum and the second conductor drum, and voltage generation means being connected to the conduction means and the core electrode.
According to the invention, the coaxial flexible piezoelectric body is in contact with the grooves of the first conductor drum and the grooves of the second conductor drum, so that the first conductor drum and the second conductor drum act as outer electrodes. Therefore, a DC voltage is applied between the conduction means for electrically connecting the first conductor drum and the second conductor drum and the core electrode by the voltage generation means, whereby the coaxial flexible piezoelectric body of the portion disposed in the grooves of the first conductor drum and the grooves of the second conductor drum can be polarized.
To solve the above-described problems, according to the invention, there is provided a polarization apparatus of a coaxial flexible piezoelectric cable, comprising a block-like conductor having a passage of a piezoelectric body tube comprising a coaxial flexible piezoelectric body formed surrounding a core electrode, move means being placed behind the block-like conductor for moving the piezoelectric body tube, and DC voltage generation means being connected to the block-like conductor and the core electrode.
According to the invention, the coaxial flexible piezoelectric body is in contact with the block-like conductor, so that the block-like conductor acts as outer electrodes. Therefore, a DC voltage is applied between the block-like conductor and the core electrode by the DC voltage generation means, whereby the coaxial flexible piezoelectric body of the portion disposed on the block-like conductor can be polarized.
Still further, the invention is intended for solving the above-described problems in the related arts and it is an object of the invention to provide a polarization apparatus and a polarization method of a coaxial flexible piezoelectric body cable for making it possible to decrease the frictional force between a piezoelectric body tube and a block-like conductor and move the piezoelectric body tube by a small force.
To solve the above-described problems in the related arts, in a polarization apparatus of a coaxial flexible piezoelectric body cable of the invention, a block-like conductor has a piezoelectric body tube passage section formed with pits and projections to lessen frictional resistance. The frictional force between a piezoelectric body tube and the piezoelectric body tube passage section can be decreased in the presence of the pits and projections and the piezoelectric body tube can be moved by a small force.
[Mode for Carrying Out the Invention]
In the polarization apparatus as in aspect 1, the coaxial flexible piezoelectric body is disposed in the grooves of the first conductor drum and the grooves of the second conductor drum, so that the first conductor drum and the second conductor drum act as outer electrodes. Therefore, a DC voltage is applied between the conduction means for electrically connecting the first conductor drum and the second conductor drum and the core electrode by the voltage generation means, whereby only the coaxial flexible piezoelectric body of the portion disposed in the grooves of the first conductor drum and the grooves of the second conductor drum, which will be hereinafter referred to as coaxial flexible piezoelectric body polarized, can be polarized.
When the coaxial flexible piezoelectric body of the portion containing a minute defect becomes coaxial flexible piezoelectric body polarized, as the core electrode and the outer electrodes are short-circuited because of discharging in the defective part, it is made impossible to apply a high voltage between the conduction means and the core electrode. However, the coaxial flexible piezoelectric body polarized after the short-circuited part leaves the first conductor drum and the second conductor drum can be again normally polarized. Therefore, if a defective part exists, an accident in which it is made impossible to polarize the whole coaxial flexible piezoelectric body does not occur. This indicates that a minute defect exists in the portion of the coaxial flexible piezoelectric body polarized of a given length, so that a minute defect existing within the given length range can be detected before the outer electrode is formed.
In the polarization apparatus as in aspect 2, the first conductor drum and the second conductor drum are rotated by the piezoelectric body tube wound by the winding means. Therefore, the first conductor drum and the second conductor drum can be rotated in the opposite directions in synchronization without the need for any special unit for rotating the first conductor drum and the second conductor drum. Since the coaxial flexible piezoelectric body polarized is polarized only for the time during which it is disposed in the grooves of the first conductor drum and the grooves of the second conductor drum, so that the polarizing time can be controlled by controlling the winding speed of the winding means.
The polarization apparatus as in aspect 3 further comprises tension application means for applying a tension to the piezoelectric body tube before the piezoelectric body tube is disposed on the first conductor drum in addition to the components as in the preceding aspects. Since a given tension is applied to the coaxial flexible piezoelectric body before the coaxial flexible piezoelectric body is disposed as the coaxial flexible piezoelectric body polarized, the coaxial flexible piezoelectric body polarized can be disposed in intimate contact with the grooves of the first conductor drum and the grooves of the second conductor drum.
The polarization apparatus as in aspect 4 further comprises discharging means for removing the surface charges of the piezoelectric body tube after the piezoelectric body tube leaves the second conductor drum in addition to the components as in the preceding aspects. The surface charges occurring during polarizing exist on the surface of the coaxial flexible piezoelectric body polarized, but are removed by the discharging means. Thus, for example, if a part of a human body touches the surface of the coaxial flexible piezoelectric body, he or she does not receive an electric shock, so that safety of work can be ensured.
The polarization apparatus as in aspect 5 further comprises capacitance detection means for detecting the capacitance between the core electrode of the piezoelectric body tube and the conduction means in addition to the components as in the preceding aspects. If the intimate contact property between the coaxial flexible piezoelectric body polarized and the grooves of the first conductor drum and the grooves of the second conductor drum is poor, for example, if the coaxial flexible piezoelectric body polarized floats up from the grooves, the capacitance between the core electrode and the conduction means decreases, so that while a DC voltage is applied therebetween for polarizing, the intimate contact property therebetween can be monitored by the capacitance detection means at the same time.
The polarization apparatus as in aspect 6 further comprises an electrical insulating partition wall surrounding the first conductor drum and the second conductor drum in addition to the components as in the preceding aspects. When a high DC voltage is applied between the conduction means for electrically connecting the first conductor drum and the second conductor drum and the core electrode, the electrical insulating partition wall prevents a human body from touching the first conductor drum or the second conductor drum, so that safety of polarizing work can be ensured.
In the polarization apparatus as in aspect 7, the electrical insulating partition wall as in aspect 6 is transparent. While the coaxial flexible piezoelectric body is being wound by the winding means and when a DC voltage is applied between the core electrode of the coaxial flexible piezoelectric body and the conduction means, the rotation state of the first conductor drum and the second conductor drum and the motion of the coaxial flexible piezoelectric body polarized can be visually observed.
The polarization apparatus as in aspect 8 further comprises warm air generation means for blowing a warm current of air into the electrical insulating partition wall in addition to the components as in aspect 6. The warm air temperature is properly controlled, whereby the temperatures of the first conductor drum and the second conductor drum can be properly controlled, so that the coaxial flexible piezoelectric body polarized can be polarized at the necessary temperature.
In the polarization apparatus as in aspect 9, the first conductor drum and the second conductor drum as in the preceding aspects are formed of stainless steel. When discharge in a defective part existing in the coaxial flexible piezoelectric body polarized occurs, the thermal evaporation amount of the stainless steel is small, so that damage to the first conductor drum and the second conductor drum caused by the discharge can be lessened.
According to the invention as in aspect 10, there is provided a polarization method wherein a coaxial flexible piezoelectric body tube of a predetermined length is disposed in such a manner that steps of disposing the coaxial flexible piezoelectric body tube in one groove of a first conductor drum and then disposing the coaxial flexible piezoelectric body tube in a groove of a second conductor drum and disposing the coaxial flexible piezoelectric body tube in another groove of the first conductor drum are repeated and then when the coaxial flexible piezoelectric body tube is wound by winding means, a DC voltage is applied between core wire of the coaxial flexible piezoelectric body tube and conduction means.
When the coaxial flexible piezoelectric body polarized is disposed in one of the grooves of the first conductor drum, the half peripheral surface of the coaxial flexible piezoelectric body polarized comes in contact with the groove and on the other hand, when the coaxial flexible piezoelectric body polarized is disposed in one of the grooves of the second conductor drum, the other half peripheral surface of the coaxial flexible piezoelectric body polarized comes in contact with the groove. Consequently, the coaxial flexible piezoelectric body polarized can be polarized over the full peripheral surface thereof.
In the polarization method as in aspect 11, in the polarization method as in aspect 10, the core wire of the piezoelectric body tube is placed at ground potential and a DC voltage is applied between the core wire and the conduction means.
When a high DC voltage is applied between the conduction means for electrically connecting the first conductor drum and the second conductor drum and the core electrode, high DC voltage portions dangerous for the human bodies can be limited to the first conductor drum and the second conductor drum, so that a partition wall, etc., can easily ensure safety of the human bodies.
In the polarization method as in aspect 12, in the polarization method as in aspect 11, the coaxial flexible piezoelectric body tube comprises core wire and a coaxial composite piezoelectric body comprising chlorinated polyethylene and ceramic piezoelectric body powder. Since this composite piezoelectric body is rich in elasticity, it can easily come in intimate contact with the grooves of the first conductor drum and the grooves of the second conductor drum.
In the polarization apparatus as in aspect 13, the piezoelectric body tube is disposed in the passage of the block-like conductor, so that the block-like conductor acts as outer electrode. Therefore, a high voltage is applied between the block-like conductor and the core electrode, whereby only the coaxial flexible piezoelectric body of the portion disposed in the passage of the block-like conductor and in a groove of the block-like conductor, which will be hereinafter referred to as coaxial flexible piezoelectric body polarized, can be polarized.
When the coaxial flexible piezoelectric body of the portion containing a minute defect becomes coaxial flexible piezoelectric body polarized, as the core electrode and the outer electrode are short-circuited because of discharging in the defective part, it is made impossible to apply a high voltage between conduction means and the core electrode. However, the coaxial flexible piezoelectric body polarized after the short-circuited part leaves the block-like conductor can be again normally polarized. Therefore, if a defective part exists, an accident in which it is made impossible to polarize the whole coaxial flexible piezoelectric body does not occur. This indicates that a minute defect exists in the portion of the coaxial flexible piezoelectric body polarized of a given length, so that a minute defect existing within the given length range can be detected before the outer electrode is formed.
The polarization apparatus as in aspect 14 further comprises heating means having a heating block involving a heater for heating the block-like conductor for heating the piezoelectric body tube disposed on the block-like conductor in addition to the components as in aspect 13. Thus, the temperature of the piezoelectric body tube can be controlled, so that the coaxial flexible piezoelectric body can be polarized at the necessary temperature.
In the polarization apparatus as in aspect 15, the passage of the piezoelectric body tube as in aspect 13 is on a face of the block-like conductor. Since the block-like conductor need not be formed with the passage of the piezoelectric body tube, working on the block-like conductor is facilitated. Since the piezoelectric body tube need not be disposed in any groove or any hole of the block-like conductor, the piezoelectric body tube can be disposed more easily.
The polarization apparatus as in aspect 16 further comprises a resistor in series with the piezoelectric body tube in addition to the components as in any one of aspects 13 to 15. When the coaxial flexible piezoelectric body of the portion containing a minute defect becomes coaxial flexible piezoelectric body polarized, the voltage applied to the coaxial flexible piezoelectric body lowers and it is made impossible to polarize. However, since current can be controlled by the appropriate resistor, damage to the DC voltage generation means is prevented. The coaxial flexible piezoelectric body polarized after the defective part of the coaxial flexible piezoelectric body leaves the block-like conductor can be again normally polarized. Therefore, if a defective part exists, an accident in which it is made impossible to polarize the whole coaxial flexible piezoelectric body does not occur. This indicates that a minute defect exists in the portion of the coaxial flexible piezoelectric body polarized of a given length, so that a minute defect existing within the given length range can be detected before the outer electrode is formed.
According to the invention as in aspect 17, there is provided a polarization method comprising the steps of first disposing a piezoelectric body tube in a passage made in a block-like conductor and then when the piezoelectric body tube stops or is moved by move means, applying a DC voltage between core wire of the piezoelectric body tube and the block-like conductor. Therefore, the block-like conductor acts as an outer electrode, so that a high voltage is applied between the block-like conductor and the core electrode, whereby only the coaxial flexible piezoelectric body of the portion disposed in the groove of the block-like conductor and in the passage of the block-like conductor can be polarized.
The piezoelectric body tube stop and move time or the move speed of the piezoelectric body tube is controlled, whereby the coaxial flexible piezoelectric body can be polarized in the necessary time.
In the invention as in aspect 18, in the polarization method as in aspect 17, while the heating block involving a heater heats the block-like conductor for heating the piezoelectric body tube disposed on the block-like conductor, a DV voltage is applied between the core wire of the piezoelectric body tube and the block-like conductor. Since the temperature of the piezoelectric body tube can be controlled, the coaxial flexible piezoelectric body can be polarized at the necessary temperature.
In the polarization method as in aspect 19, in the polarization method as in aspect 17 or 18, the core wire of the piezoelectric body tube is placed at ground potential and a DC voltage is applied between the core wire and the block-like conductor. When a high DC voltage is applied between the block-like conductor and the core electrode, high DC voltage portions dangerous for the human bodies can be limited to the block-like conductor, so that a partition wall, etc., can easily ensure safety of the human bodies.
In the polarization apparatus as in aspect 20, a groove is provided as the passage of the piezoelectric body tube as in aspect 13. Since the passage placed in the block-like conductor is a groove, the top is opened and the piezoelectric body tube can be easily disposed from above the groove.
In the polarization apparatus as in aspect 21, a cover is placed on the groove of the piezoelectric body tube passage in addition to the components as in aspect 20. When the block-like conductor is heated for heating the piezoelectric body tube disposed in the block-like conductor, the cover blocks heat from escaping from the top of the groove. Thus, the temperature of the piezoelectric body tube can be controlled, so that the coaxial flexible piezoelectric body can be polarized at the necessary temperature.
In the polarization apparatus as in aspect 22, a hole is provided as the passage of the piezoelectric body tube as in aspect 13. When the block-like conductor is heated for heating the piezoelectric body tube disposed in the block-like conductor, the piezoelectric body tube placed in the hole is heated uniformly from the surroundings. Thus, the temperature of the piezoelectric body tube can be controlled, so that the coaxial flexible piezoelectric body can be polarized at the necessary temperature.
The polarization apparatus as in aspect 23 further comprises a resistor in series with the piezoelectric body tube in addition to the components as in any one of aspects 13, 14, and 20 to 22. When the coaxial flexible piezoelectric body of the portion containing a minute defect becomes coaxial flexible piezoelectric body polarized, the voltage applied to the coaxial flexible piezoelectric body lowers and it is made impossible to polarize. However, since current can be controlled by the appropriate resistor, damage to the DC voltage generation means is prevented. The coaxial flexible piezoelectric body polarized after the defective part of the coaxial flexible piezoelectric body leaves the block-like conductor can be again normally polarized. Therefore, if a defective part exists, an accident in which it is made impossible to polarize the whole coaxial flexible piezoelectric body does not occur. This indicates that a minute defect exists in the portion of the coaxial flexible piezoelectric body polarized of a given length, so that a minute defect existing within the given length range can be detected before the outer electrode is formed.
According to the invention as in aspect 24, there is provided a polarization method comprising the steps of first disposing a piezoelectric body tube in a passage made in a block-like conductor and then when the piezoelectric body tube stops or is moved by move means, applying a DC voltage between core wire of the piezoelectric body tube and the block-like conductor. Therefore, the block-like conductor acts as an outer electrode, so that a high voltage is applied between the block-like conductor and the core electrode, whereby only the coaxial flexible piezoelectric body of the portion disposed in the groove of the block-like conductor and in the passage of the block-like conductor can be polarized.
The piezoelectric body tube stop and move time or the move speed of the piezoelectric body tube is controlled, whereby the coaxial flexible piezoelectric body can be polarized in the necessary time.
In the invention as in aspect 25, in the polarization method as in aspect 24, while the heating block involving a heater heats the block-like conductor for heating the piezoelectric body tube disposed on the block-like conductor, a DV voltage is applied between the core wire of the piezoelectric body tube and the block-like conductor. Since the temperature of the piezoelectric body tube can be controlled, the coaxial flexible piezoelectric body can be polarized at the necessary temperature.
In the polarization method as in aspect 26, in the polarization method as in aspect 24 or 25, the core wire of the piezoelectric body tube is placed at ground potential and a DC voltage is applied between the core wire and the block-like conductor. When a high DC voltage is applied between the block-like conductor and the core electrode, high DC voltage portions dangerous for the human bodies can be limited to the block-like conductor, so that a partition wall, etc., can easily ensure safety of the human bodies.
According to the invention as in aspect 27, there is provided a polarization apparatus of a coaxial flexible piezoelectric body cable, comprising a block-like conductor having a passage section of a piezoelectric body tube comprising a coaxial flexible piezoelectric body formed surrounding a core electrode, the passage section being made uneven like pits and projections, and DC voltage generation means being connected to the block-like conductor and the core electrode. The piezoelectric body tube is disposed in the passage section of the block-like conductor so that the block-like conductor acts as outer electrodes. Therefore, a high voltage is applied between the block-like conductor and the core electrode, whereby the coaxial flexible piezoelectric body of the portion disposed in the block-like conductor can be polarized. The piezoelectric body tube passage section of the block-like conductor is made uneven like pits and projections. To move the piezoelectric body tube, the frictional force between the piezoelectric body tube and the piezoelectric body tube passage section can be decreased in the presence of the pits and projections and the piezoelectric body tube can be moved by a small force.
In the polarization apparatus as in aspect 28, the block-like conductor is provided with a heater in addition to the components as in aspect 27. The block-like conductor is heated by the heater for heating the piezoelectric body tube disposed in the block-like conductor and the temperature of the piezoelectric body tube can be controlled, so that the coaxial flexible piezoelectric body can be polarized at the necessary temperature.
The polarization apparatus as in aspect 29 is the polarization apparatus of a coaxial flexible piezoelectric body cable as in aspect 27 or 28 wherein wire netting is disposed on the block-like conductor to provide the passage section of the piezoelectric body tube. The metal netting is used to form pits and projections, so that the frictional force between the piezoelectric body tube and the piezoelectric body tube passage section can be decreased and the piezoelectric body tube can be moved by a small force without forming the disposition surface of the piezoelectric body tube like pits and projections.
The polarization apparatus as in aspect 30 is the polarization apparatus of a coaxial flexible piezoelectric body cable as in aspect 27 or 28 wherein the block-like conductor is formed with a groove formed with pits and projections and the piezoelectric body tube is disposed in the groove formed with pits and projections. If the block-like conductor is heated, the piezoelectric body tube disposed in the groove of the block-like conductor is heated from the bottom and both walls of the groove. Thus, the piezoelectric body tube is heated more evenly, so that the coaxial flexible piezoelectric body can be polarized at the necessary temperature. The top is opened and the piezoelectric body tube 403 can be easily disposed from above the groove.
The polarization apparatus as in aspect 31 is the polarization apparatus of a coaxial flexible piezoelectric body cable as in aspect 27 or 28 wherein the block-like conductor is formed with a groove on which wire netting is disposed and the piezoelectric body tube is disposed in the groove on which the wire netting is disposed. The piezoelectric body tube is disposed in the groove on which the wire netting is disposed, whereby the piezoelectric body tube and the wire netting come in point contact with each other. Thus, the frictional force between the piezoelectric body tube and the piezoelectric body tube disposition face can be decreased and the piezoelectric body tube can be moved by a small force.
According to the invention as in aspect 32, there is provided a polarization method comprising the steps of disposing a piezoelectric body tube in a passage section of a block-like conductor and applying a DC voltage between core wire of the piezoelectric body tube and the block-like conductor. Therefore, the block-like conductor acts as an outer electrode, so that a high voltage is applied between the block-like conductor and the core electrode, whereby the coaxial flexible piezoelectric body of the portion disposed in the block-like conductor and in the passage section of the block-like conductor can be polarized. The piezoelectric body tube passage section of the block-like conductor is made uneven like pits and projections to lessen frictional resistance. The piezoelectric body tube and the piezoelectric body tube passage section come in point contact with each other in the presence of the pits and projections. Thus, the frictional force between the piezoelectric body tube and the piezoelectric body tube disposition face can be decreased and the piezoelectric body tube can be moved by a small force. The piezoelectric body tube stop and move time or the move speed of the piezoelectric body tube is controlled, whereby the coaxial flexible piezoelectric body can be polarized in the necessary time.
In the invention as in aspect 33, in the polarization method as in aspect 32, while the heating block involving a heater heats the block-like conductor for heating the piezoelectric body tube disposed on the block-like conductor, a DV voltage is applied between the core wire of the piezoelectric body tube and the block-like conductor. Since the temperature of the piezoelectric body tube can be controlled, the coaxial flexible piezoelectric body can be polarized at the necessary temperature.